Susan Biddle Ross is a character on Seinfeld, played by Heidi Swedberg.
Susan, an executive at NBC, first appeared in the season 4 episode "The Pitch", in which Jerry Seinfeld and George Costanza pitched the idea for their sitcom to Susan and her fellow executives. Over the course of the fourth season, as the development of the sitcom continued, Susan began dating George - an endeavor that was not helped by Cosmo Kramer, who first vomited on Susan, and then burned down her father's cabin. After George absent-mindedly kissed her during a meeting with NBC, the network fired her, leading her to break up with him.

They briefly got back together in "The Pick", but George decided he did not want to be in a relationship with her after all, and deliberately picked his nose so she would dump him. The next time he saw her, she was in a lesbian relationship, and George presumed he had driven her to it. Susan's lover was seduced by Kramer. After an airing of George and Jerry's pilot received negative reviews and a power change at NBC that left Susan out of work, she left George's life.

They were reunited in the season 7 premiere, "The Engagement", and on a whim, George proposed to her. (Her lesbianism, as George put it, "didn't take.") The engagement lasted the whole of the seventh season, with George eventually realizing that he was trapped - particularly when a potential relationship with Marisa Tomei was ruined because of it - and trying every method to get out of the relationship. Ultimately, in the season finale, "The Invitations", George's choice of low quality wedding invitations proved to be his saving grace: the low-quality glue on the invitations proved overpowering to Susan as she used her tongue to moisten and seal them all, ultimately giving her an overdose and killing her. George wasted no time in calling Marisa Tomei; however, she was no longer interested.

In the aftermath of her death, Susan's parents organized a foundation in her honor and appointed George to be on the board, a position he did not relish. The Rosses continued to be a part of his life through to "The Finale" when—at a court case against George, Kramer, Jerry and Elaine Benes—they learned that he was the one who chose the invitations, and of his relief at her death.

Susan reappeared in a flashback in the season nine episode "The Betrayal", an episode which went backwards, in a brief appearance at the end (set during the engagement).